Circular saw



(No Model.)

O. H. DOUGLAS.

GIRGULAR SAW. No. 274,922. Patented Apr.-3,1883.

* Fiq- 1= Y WITNESSES: INVENTOR I W yzm /w I 2 2 3 ATTORNEY TERS. Plwlo-uthugrnpher. Washington, b. c. l

' UNITED STATES PATENT OFFI E.

CHARLES H. DOUGLAS, OF CHICAGO, ILLINOIS.

CIRCULAR SAW.

SPECIFICATION forming part of Letters Patent No. 274,922, dated April 3,1883.

' Application filed February 1, 1883. (No model.)

,To all whom it may concern B'e-it known that I, CHARLES H. DOUGLAS,

1 a citizen of the United States, residing at smooth as machine-planingdirect from the' Chicago, in the county of Cook and, State of Illinois,have invented a new and useful'lmprovement in Saws, of which thefollowing is a specification.

"The object of my invention is to make a saw that will easilycut.through a piece of timber without scoring or roughing the sides ofthe kert, and thereby'produce lumber as saw with even less power than isrequired to produce rough lumber with the'saws in 001D mon use. I attainthis objectby the form ments; Fig. 2, an edge view of the same; Fig.

3, a vertical section through Fig. 1 at :r w, and Fig. 4 an enlargedview of Fig. 8.

Similar letters refer to similar parts in the several views.

On one side of the .back. of each tooth there is a slight narrowprojection or rib, or, which has a flat surface nearly or quite parallelwith the side of the sawr'vhich serves (instead of the usual set) towiden the saw-kerf for the freerunning of the saw, but, unlike the usualset, has a flat surface, (instead of a point,) and therefore leaves thelumber it saws quite as smooth as machine-planing. ()n the other side ofeach tooth, opposite to rib a, there is a bevel, b, which reduces thewidth of the cutting point or edge, and the thickness of the back ofeach tooth to about half the width of the kerf. This bevel is on theopposite side of each alternate tooth, and consequently one tooth cuts achip half the width of .the kerf,

and the next tooth following cuts the remaining half. Thus the cut isdivided, and less power is required to run the saw than if each toothcut the entire width of the kerf. The back of each tooth is made on aslight and accurate incline or angle to the line of cut for the purposeof leaving itfinished to the exact form and clearance required for themost perfect chisel cut. By this device all the dressing forthe purposeof sharpening is done on the front of the tooth, and the saw will remainaccurately jointed until the teeth .are

worn up; also, the chip is taken out with a clean shaving cut, insteadof breaking it into sawdust, as is done by the present form ofsaw-tooth. These improvements are not confined to any form of saw.

The difference between my saw and all others is,in the peculiar form andconstruction ofthe teeth, mine having a rib, a, on one side and a bevel,b, on the other side of the back of each tooth, togetherwith a slightand uniform angle to the line of cut given to the backs of all theteeth, all or any of which points or devices are not found in othersaws. The rib a is an improvement upon the projection claimed in myetters Patent ot'g a nuary 25, 1881, No. 236,8 for-an i'niifiii vemeutin saws for accomplishing the same desired result, the principaldiii'erence being in the' shape. I therefore use the term rib in thisspecification merely to cover the im provement' upon the said projectionalready patented.

I claim- 1. A circular saw provided with teeth substantially of thecharacter described, said teeth having the rib a at one side andextending nearly in a circumferential direction, and i being beveled, asat b, on the opposite face, substantially as described.

2. The saw-tooth having a rib, a, at one side and bevel b at the otherside, the rearportion being slightly below the front portion of thetooth, substantially as set forth.

3. A circular saw provided with teeth having ribs on one side andbeveled surfaces on the other side, each succeeding toozh having theribs and bevels reversed with reference to the preceding one,substantially as described.

CHARLES H. DOUGLAS. Witnesses:

WM. '1. 001mm,

J osnrn WARBURTON.

